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Biomedical subjects

S E Abram

Publications and source records attributed to S E Abram.

At least 19 recordsLinked to original sources

Intrathecal acetyl cholinesterase inhibitors produce analgesia that is synergistic with morphine and clonidine in rats.

Intrathecal (IT) administration of acetyl cholinesterase inhibitors produces analgesia through a muscarinic action. The addition of IT cholinergic agonists to IT opioids or alpha 2-adrenergic agonists results in enhanced analgesic effects, but it is not clear whether these interactions are synergistic, additive, or less than additive. Dose-response curves for hot plate and tail immersion tests were established for IT neostigmine, physostigmine, and echothiophate in rats. Dose-response curves for hot plate testing were established for IT morphine and clonidine. The effect of maximally effective doses of each of the three cholinergic drugs on hot plate testing was plotted over time. Isobolographic analysis was performed for hot plate testing using neostigmine-morphine and neostigmine-clonidine combinations. The three cholinesterase inhibitors produced profound analgesia on hot plate testing but incomplete analgesia using the tail immersion test. Duration of analgesia on hot plate testing ranged from 45 min for physostigmine to more than 24 h for echothiophate. IT administration of combinations of neostigmine plus morphine and neostigmine plus clonidine both produced significantly more profound analgesia than the calculated additive effects and are, therefore, synergistic in their actions.

Analgesia

Characteristics of the analgesic effects and drug interactions of intrathecal carbachol in rats.

BACKGROUND: Intrathecal carbachol produces consistent analgesia in animals without appreciable adverse effects. Little is known about the ability of this drug to provide analgesia as stimulus intensity is increased. Likewise, there are few data regarding interactions between carbachol and other intrathecal analgesics. METHODS: Using two different noxious radiant heat intensities, one applied to each hind limb, analgesic effects of 1, 3, 10, and 30 micrograms intrathecal carbachol on paw withdrawal latencies were measured. Similar testing was done for intrathecal morphine and clonidine. ED50 fractions (1/2, 1/4, 1/8, 1/16) of drug combinations of carbachol-morphine and carbachol-clonidine were administered, responses to the low intensity stimulus were recorded, and the ED50 of each combination was established and isobolographic analysis of the drug interactions was carried out. RESULTS: The 30-micrograms dose of carbachol was associated with transient agitation, salivation, and hind limb weakness. No other adverse effects were noted. The ED50 (95% confidence interval) of intrathecal carbachol was 2.34 micrograms (1.34-4.04) for low intensity stimulation and 12.64 micrograms (4.18-38.25) for high intensity. There was no significant difference between high- and low-intensity ED50 values for intrathecal morphine and clonidine. The analgesic effect of the carbachol-morphine and carbachol-clonidine combinations were significantly greater than the calculated additive effects. The ED50 for the carbachol-morphine combination was 12% of the expected additive value and the ED50 for the carbachol-clonidine combination was 30% of the expected additive value. CONCLUSIONS: Intrathecal carbachol provides analgesia to noxious thermal stimulation of the hind paw in rats. It is relatively less effective at providing analgesia than intrathecal morphine or clonidine when stimulus intensity is raised. Intrathecal carbachol is synergistic when combined with intrathecal morphine or clonidine.

Analgesics, Non-Narcotic

Substance abuse by anesthesiology residents.

A 1989 cross-sectional substance abuse survey of 260 former anesthesiology residents of the Medical College of Wisconsin (MCW) during the previous 30 years yielded 183 responses (70.3%). Over three-fourths (77.2%) of those who responded reported that they had used alcohol when they were residents; 20.0% had used marijuana; and 15.7% had used cocaine. Forty-three of the 178 respondents had used unprescribed psychoactive drugs. Twenty-nine (15.8%) had been self-admitted problematic substance abusers during their residencies: 23, alcohol dependent and six, drug dependent; among the latter were four with a dual (alcohol and drug) dependency. More than 85% considered the drug policy information available during their residencies had been inadequate; institutional drug-control policies were rated "fair-to-poor" by more than 70%. Thirty-five of the residents had observed their teachers using alcohol and/or other drugs to the detriment of their teaching; approximately one-third of these infractions had gone unreported.

Adolescent

Educational role of cancer pain rounds.

Lack of appropriate physician education is one of several reasons for the recognized deficits in cancer pain management. This article describes the educational role of a weekly meeting, "Cancer Pain Rounds," attended by a multidisciplinary team of health professionals skilled in cancer pain management and student physicians caring for inpatients with cancer. Educational benefits occur in three spheres including factual information concerning assessment, treatment, and attitude issues, legitimization of the cancer pain problem, and role modeling. This type of educational experience will hopefully improve cancer pain management.

Analgesia

Spinal cord metabolic response to noxious radiant heat stimulation of the cat hind footpad.

The 2-deoxy[14C]glucose (2-DG) method was used to study glucose utilization in the cat lumbar spinal cord during noxious thermal stimulation to the hind footpad. Spinal cord glucose utilization in stimulated cats was twice that of control animals. Diffusely increased metabolic activity was seen in the ipsilateral dorsal horn. The highest levels of 2-DG were seen in the ipsilateral ventral horn, while a moderate increase was seen in the contralateral ventral horn.

Animals

Cardiovascular responses to noxious radiant heat in anesthetized cats.

The responses of heart rate and blood pressure to noxious radiant heat were studied in seven pentobarbital-anesthetized cats. Afferent activity recorded from the tibial nerve, systemic blood pressure, and heart rate were monitored as skin temperature of the hind footpad was raised to 53 degrees C for 20 s using radiant heat. The averaged tibial afferent nerve activity increased markedly as skin temperature approached 52 degrees C. Within 2-3 s of the onset of increased tibial nerve activity, systolic blood pressure increased an average of 32 mmHg and heart rate increased an average of 16 beats/min in the seven animals that were studied. The results of this study provide evidence for a somatosympathetic reflex that is initiated by cutaneous nociceptors. Under pentobarbital anesthesia, an increase in heart rate and blood pressure appears to be a reliable indicator of nociceptor activation.

Afferent Pathways

Chronic pain therapy with transcutaneous electrical nerve stimulation: predictive value of questionnaires.

A retrospective study of 200 chronic pain patients was conducted to determine whether preexisting physical or social factors influence treatment success with transcutaneous electrical nerve stimulation (TENS). Responses to 30 questions from a preadmission questionnaire were analyzed against short-term treatment success. Patients with pain of more than a year's duration, who had undergone multiple surgical operations for pain control, who used tranquilizers, or who were not working because of pain, demonstrated a generally lower rate of treatment success, although the differences were not statistically significant. Treatment success rate was significantly higher for retired patients than for those with blue-collar jobs or those who were unemployed. There was no association between treatment success rate and site, frequency, character or severity of pain, age, sex, use of narcotic analgesics, or the presence of financial compensation or litigation. The value of TENS for chronic pain remains largely empirical.

Adolescent

Altered neural conduction with epidural bupivacaine.

The sites and magnitude of evoked potential response alterations induced by varying masses and concentrations of epidurally administered bupivacaine were assessed from electrodes positioned along the conducting pathways of the monkey. The mass of bupivacaine was the major factor in determining the level and degree of response alterations. At the lower levels of total drug mass, effects were limited to the dorsal root entry zone, whereas higher levels of mass not only increased the response attenuation at the gray matter level but resulted in additional changes in those responses recorded from the spinal cord white matter tracts. With all other factors stable, increasing concentration was associated with a greater degree of response attenuation, especially at the lower levels of total mass. These findings indicate that the mass of the drug is the major factor in determining the magnitude and level of bupivacaine-induced epidural analgesia. Increased concentration influences the local anesthetic's penetration at the dorsal root entry zone and, to a lesser degree, at the white tracts of the spinal cord.

Anesthesia, Epidural

Failure of naloxone to reverse analgesia from transcutaneous electrical stimulation in patients with chronic pain.

To investigate the possible role of endogenous opiates in the mediation of analgesia produced by low intensity, high frequency transcutaneous electrical stimulation in the presence of chronic pain, an attempt was made to reverse stimulation-induced analgesia with naloxone. Fifteen patients with chronic pain who were consistently relieved of pain by low intensity, high frequency transcutaneous stimulation were studied. During stimulation at 58 Hz, patients were given double-blind intravenous injections of either naloxone (0.4 or 1.2 mg) or saline. Subjective pain ratings were recorded before stimulation, after stimulation, and after naloxone and saline injections. No reversal of analgesia was seen after naloxone or saline. These results suggest that transcutaneous stimulation at low intensity and high frequency may provide analgesia that is not associated with release of endogenous opiates in patients with chronic pain.

Adult